Introduce Dagger.

Start off with the simple stuff, just providing unitialised managers
and having Main do all the wiring. Update the tests to match.

Change-Id: I0e86451a7a719d514fa1fed0c79aa4fe45134477
Reviewed-on: http://gerrit.dmdirc.com/2679
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager